(1) Field of the Invention
The present invention relates to an electrical power supply and control device for equipment of a rotor, and to an aircraft fitted with such a device.
The invention thus lies in the technical field of electrical power supply and control means for equipment present on a rotary rotor, with passage from a stationary frame of reference to a rotary frame of reference. More particularly, the technical field is that of electrical power supply and control means for de-icing and anti-icing means of a rotorcraft rotor.
(2) Description of Related Art
A first device is known that has an alternating current (AC) generator connected to an electrical unit sometimes referred to as a “power de-icing” unit. The electrical unit is provided in particular with a rectifier and a sequencer for powering a plurality of electric cables in a predetermined sequence. Furthermore, for safety reasons, the electrical unit is duplicated.
The generator and the electrical unit are installed in a stationary frame of reference, i.e. in the airframe of the aircraft.
Consequently, the first device includes slip rings comprising a non-rotary portion and a rotary portion connected together by brushes. By way of example, the non-rotary portion possesses circular electrical tracks known as slip rings that are powered electrically by electric cables coming from the electrical unit, with the rotary portion having respective brushes running along each of the slip rings.
The rotary portion then powers a plurality of heater mats for each blade in the sequence that is programmed in the electrical unit for the purpose of de-icing or of preventing ice forming on the blade, each mat being connected by an electric cable to a brush of the rotary portion of the slip rings.
That first device combining an electrical unit with slip rings is very heavy, in particular because of the large number of electric cables and slip rings.
That first device can therefore easily be installed on a powerful heavy rotorcraft. However installing such a device on a medium weight rotorcraft may reduce the number of passengers by two, for example.
Furthermore, the friction between each brush and the corresponding slip ring tends to degrade the performance of the slip rings. Maintenance actions requiring the device to be dismantled then need to be undertaken relatively frequently. Unfortunately, the slip rings are sometimes difficult to access, and the cost of maintenance may be high, requiring the rotorcraft to be grounded for a long time.
Finally, it should be observed that since the electrical unit is installed in the airframe of the aircraft, the electrical unit is likely to disturb nearby electrical equipment. Furthermore, the electrical unit presents non-negligible bulk and is therefore penalizing.
Document U.S. Pat. No. 7,602,081 presents a second device having a control unit arranged in a stationary frame of reference, the control unit being connected to slip rings.
Those slip rings then power electrical equipment via a distributor unit arranged in a rotary frame of reference.
The control unit then generates electricity that is transmitted to the distributor unit via the slip rings, the slip rings acting as an interface between the rotary frame of reference and the non-rotary frame of reference, the distributor unit converting the electricity it receives and powering the electrical equipment as a function of electrical signals that reach it.
Document US 2006/0226292 also uses slip rings with brushes.
Finally, document U.S. Pat. No. 5,519,275 presents a rotary power transformer allowing information to be transmitted via a carrier current.
Carrier current technology is advantageous. Nevertheless, the data transmission rate and the observed interference limit that technology to restricted applications.
It should be observed that the same applies to slip rings. It is difficult to cause a low power signal coming from a temperature or ice sensor, for example, to transit via slip rings or a carrier current.
It should be observed that the state of the art also includes document U.S. Pat. No. 5,572,178 and document EP 1 541 467 relating to a modular de-icing/anti-icing device for an airfoil surface.